20 September 1996

Higher cutting heights?

CUTTING heights may have to be raised after heavy showers have splashed soil up maize stems.

"Soil contamination will cause secondary fermentation and spoilage in the silage," says Maize Growers Association agronomist Simon Draper.

He says the minimum cutting height should be 15cm (6in). Below this the stem has a high moisture content.

The lower part of the stem is also woody and of little feed value. It makes consolidation more difficult and raising the cutting height to 20cm (8in) increases dry matter and starch percentages.

Chop length is also critical in improving consolidation and hence fermentation and digestibility.

"The maximum chop length should not exceed 2cm (0.75in) and the majority should be less than 0.75cm (0.25in) if possible."

This requires sharp harvester knives and continual checking of chop length.

The crop should be spread as it is dropped in to the clamp in 15cm (6in) layers or less. And the clamp should be filled within two days. When it takes longer the clamp should be split, he adds. He advises using the heaviest tractor available to run over the harvested material in the clamp.